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Updated: Mar 27, 2026
Author Spotlight: Controlled Human Exposure Model for Tick Research and Lyme Disease Studies
Published on: December 1, 2023
Effectiveness of Residential Acaricides to Prevent Lyme and Other Tick-borne Diseases in Humans
Alison F Hinckley1, James I Meek2, Julie A E Ray2
1Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, Fort Collins, Colorado.
Background:
In the northeastern United States, tick-borne diseases are a major public health concern. In controlled studies, a single springtime application of acaricide has been shown to kill 68%-100% of ticks. Although public health authorities recommend use of acaricides to control tick populations in yards, the effectiveness of these pesticides to prevent tick bites or human tick-borne diseases is unknown.
Methods:
We conducted a 2-year, randomized, double-blinded, placebo-controlled trial among 2727 households in 3 northeastern states. Households received a single springtime barrier application of bifenthrin or water according to recommended practices. Tick drags were conducted 3-4 weeks after treatment on 10% of properties. Information on human-tick encounters and tick-borne diseases was collected through monthly surveys; reports of illness were validated by medical record review.
Results:
Although the abundance of questing ticks was significantly lower (63%) on acaricide-treated properties, there was no difference between treatment groups in human-tick encounters, self-reported tick-borne diseases, or medical-record-validated tick-borne diseases.
Conclusions:
Used as recommended, acaricide barrier sprays do not significantly reduce the household risk of tick exposure or incidence of tick-borne disease. Measures for preventing tick-borne diseases should be evaluated against human outcomes to confirm effectiveness.
